Electrically heated tool



1955 1.. H. THOMAS ELECTRICALLY HEATED TOOL Filed June 22, 1953 INVENTOR. LAURENCE H.THOMAS ATTORNEYS United States Patent ELECTRICALLY HEATED TOOL Laurence H. Thomas, Birmingham, Mich., assiguor to American Electrical Heater Company, Detroit, Mich., a corporation of Michigan Application June 22, 1953, Serial No. 362,982

4 Claims. (Cl. 219-26) The invention relates to electrically heated tools and more particularly to soldering irons of that type in which the tool proper or electrically heated tip is replaceably connected to the handle portion. It is the object of the invention to obtain a construction in which the tip when in use is rigidly secured to the handle while at the same time it is easily detachable for replacement. To this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Fig. 1 is a central longitudinal section through the tool;

Fig. 2 is an enlarged section of the tip portion;

Fig. 3 is a cross section on line 3-3, Fig. 1;

Fig. 4 is a perspective view of the tapered sleeve segments.

The tool as a whole includes a handle A formed of non-metallic material having relatively low thermal conductivity, a tubular metallic shank B and the electrically heated tool proper or tip C. The tubular shank B is detachably connected to the handle A by a threaded end portion B which is screwed into a nut portion A within the handle which is hollow. As shown, the nut A bears against a shoulder A and is secured by an insert A within a cylindrical recess in the handle extending through the outer end thereof. The insert A is also hollow and incloses an insulator mounting D. This mounting is rigidly secured to the end of the tubular shank B and serves for securing the electrical connections between the terminal conductors within the flexible cable E and the terminals of the electrical heating unit F within the tip C. Thus, when a tip is to be replaced the handle A is easily detached from the tubular shank B so as to expose the insulator mounting D and permit of detaching the terminals of the tip to be removed and attaching the terminals of the replacement tip.

The tip C includes a tapering end portion C which forms the soldering tool and a hollow cylindrical portion C which contains the heating unit F. The latter may, if desired, be detachable from the tip but as specifically illustrated it forms a permanent part thereof. The tip C is formed of copper or a high percentage copper alloy and is also provided with an electrolytically deposited surface coating of iron which very greatly increases its resistance to corrosion when under heat. The unit F includes a cylindrical core member F of ceramic material, a resistor F wound as an open coil upon the core, a head F also of ceramic material recessed to receive the end of the core F and holding the latter concentrically spaced from the portion C and a filling F of insulating refractory material preferably magnesium oxide. This material is retained within the hollow portion C by a ceramic head F and the latter is retained by an annular turned in flange C at the end of the portion C The terminal connectors G of the resistor F extend through spaced apertures in the head F and then extend through separate passages in a member G of insulating material. The latter extends completely through the tubular shank B and threaded end portion B thereof bringing the terminals G in proximity to the mounting D.

For rigidly but detachably securing the tip C to the hollow shank B, I have devised the following construction:

The shank B has an end portion B enlarged in diameter to surround the end portion of the member C with an annular space therebetween. Within this space is placed a bushing H formed of separate segments which have at one end a head of T-shaped cross-section forming inwardly and outwardly extending segmental flanges H and H The flanges H engage an annular groove C in the member C so as to be locked against axial movement relative thereto. The outer face of each segment is tapered or conical so that when forced inward in the portion B of the tubular shank B it will form a wedging engagement therewith. I is a clamping collar which is internally threaded to engage external threads on the portion B and which is also provided with an inwardly extending flange I engaging the flange H of the segments H. Thus, as the collar I is screwed onto the member 13 it will force the segments H into wedging engagement and form a rigid connection between the member C and the tubular shank B. To positively lock the members C and B against relative rotation, the member B is indented to force a portion B into the space between adjacent segments H, holding the latter from rotation.

The attachment means just described locks the members B and C against any relative axial movement and also against any relative rotary movement. Consequently the tip is rigidly secured to the tubular shank B and handle A all the time that it is in service. However, if it is desirable to replace the tip all that is necessary to detach it from the shank B is to unscrew the clamping collar I. Detachment of the terminals G may be easily accomplished by unscrewing the nut A of the handle from the head B and then slipping the handle back on the flexible conductor E until the mounting head D is exposed. This head has conductor plates I on opposite sides thereof to which the terminals G and conductors of the flexible cable E are attached by screws J.

What I claim as my invention is:

1. In an electrically heated tool of the type including a handle member and a tip provided with an internal heating unit rigidly but detachably secured to said handle member; attachment means for said members comprising a hollow tubular shank secured to the handle member and having a portion of an internal diameter in excess of the external diameter of said tip surrounding a portion of the latter, and a sleeve formed of separate segments fitting about said tip each having at its outer end an inwardly extending flange engaging a groove in said tip forming a shouldered engagement therewith preventing relative axial movement, the external surface of said sleeve being tapered to engage said shank, and a collar having an external screw threaded engagement with said shank and an inner shoulder engagement with the outer end of said sleeve adapted to rigidly clamp said tip to said shank and lock the same against relative axial displacement.

2. The construction as in claim 1 in which said shank has an indented portion projecting between said segments to prevent relative rotation thereof.

3. The construction as in claim 1 in which the handle member is hollow, an insulator mounting member is within the hollow handle and rigidly secured to the end of said tubular shank, terminal conductors of said heating unit extending through said tubular shank into the hollow handle member, an insulator tube having separate passages enclosing the portions of said terminal, conductors within said tubular shank, an external conductor References Cited in the file of this patent cable extending into said hollow handle, and connections a a UNITED STATES PATENTS between the conductors of said cable and terminal conductors secured to said insulator mounting. 1,316,368 Kuhn 6t Sept, 919

4. The construction as in claim 1 in which the harrdle 5 1378324 Clark et y 1921 is hollow and a conductor cord extends thereinto and 1,708,995 Abbott P 1929 in which said tip comprises a tool member having a solid 181O164 Fay et a1 111116 1 outer end portion and an integral hollow cylindrical rear 1,860,192 Lockwood y 1932 portion with an open end, a core of ceramic material 2,213,433 Young p 3, 1940 centrally within said cylindrical portion, an electrical 10 2,274,408 Hampton et a1 1 1942 resistor wound upon said core, refractory insulating ma- 2,311,776 Powell 23, 9 terial surrounding said resistor and packed within said 215051625 Nofdstrom P 1950 hollow cylindrical portion, a ceramic head closing the 2,552,193 Lennox y 8, 1951 open end and an inturned flange on said cylindrical por-- 2,588,531 Johnson Man 11, 1952 tion retaining said head, the terminals of said resistor be- 15 2,658,983 10, 1953 2,679,223 Franklin May 25, 1954 ing spaced and passing through said head for electrical connection with said conductor cord within said hollow handle. 

